Increased fatty acid accumulation following overexpression of glycerol‐3‐phosphate dehydrogenase and suppression of β‐oxidation in oleaginous fungus Mortierella alpina

Abstract

Mortierella alpina is an industrial oleaginous fungus. Although its fatty acid synthesis pathways have been thoroughly examined, the mechanism for fatty acid accumulation is still not fully understood. In this study, we analyzed the effect of glycerol‐3‐phosphate (G3P) supply and β‐oxidation suppression during fatty acid accumulation. The NAD+‐dependent glycerol‐3‐phosphate dehydrogenase coding gene was cloned from M. alpina ATCC 32222 and overexpressed in this organism. Lipid analysis via GC‐MS revealed that overexpression of G3PD1 resulted in a 50% increase in fatty acid content, whereas G3PD2 exerted a less significant effect and G3PD3 had no effect. Simultaneous supplementation with carnitine O‐acetyltransferase inhibitor, R‐etomoxir, further improved fatty acid accumulation up to 49.4% of dry cell weight. Practical applications: Our results suggest that G3PD1 plays an important role during fatty acid accumulation in M. alpina. Suppression of β‐oxidation can significantly increase fatty acid accumulation. These findings have obvious implications for biotechnological strategies to increase the overall level of oil production. Simultaneously, overexpressing G3PD1 and inhibiting genes involved in fatty acid β‐oxidation may be a step forward to achieving further improvements in fatty acid accumulation in M. alpina. G3PD1, catalyzing G3P to DHAP conversion, plays the most important role during fatty acid accumulation in M. alpina compared to G3PD2 and G3PD3.

Fatty Acids and their Derivatives as Renewable Platform Molecules for the Chemical Industry

“…[256,257] Again similar approaches were used to optimize oil production in the marine diatom Phaeodactylum tricornutum,inthe heterokont oleaginous microalga Nannochloropsis oceanica,a nd in the oleaginous fungus Mortierella alpina. [258][259][260][261]…”

“…By additional silencing of the TAG degrading lipase SDP1, accumulation could be increased up to 33 % in tobacco and up to 8.4 % in sorghum leaves [256, 257] . Again similar approaches were used to optimize oil production in the marine diatom Phaeodactylum tricornutum , in the heterokont oleaginous microalga Nannochloropsis oceanica , and in the oleaginous fungus Mortierella alpina [258–261] …”

Fettsäuren und Fettsäurederivate als nachwachsende Plattformmoleküle für die chemische Industrie

“…Wenn zusätzlich die Expression der TAG‐abbauenden Lipase SDP1 unterdrückt wurde, konnte die Anreicherung um bis zu 33 % in Tabak und um 8,4 % in Hirse erhöht werden [256, 257] . Ähnliche Ansätze wurden auch schon verwendet, um die Ölproduktion in der Kieselalge Phaeodactylum tricornutum , in der ölhaltigen Mikroalge Nannochloropsis oceanica und im ölspeichernden Pilz Mortierella alpina zu optimieren [258–261] …”

“…[256,257] ¾hnliche Ansätze wurden auch schon verwendet, um die Ölproduktion in der Kieselalge Phaeodactylum tricornutum,i nd er çlhaltigen Mikroalge Nannochloropsis oceanica und im çlspeichernden Pilz Mortierella alpina zu optimieren. [258][259][260][261]…”

The role of MTHFDL in mediating intracellular lipogenesis in oleaginous Mortierella alpina

“…Our transcriptomics analysis identified glucose-6-phosphate dehydrogenase (G6PD) coupled with 6-phosphogluconate dehydrogenase (PGD) as the prime alternative provider of NADPH, which is one of the major features that enables efficient lipid biosynthesis in oleaginous micro-organisms [9]. Our laboratory further proved that ME, G6PD and PGD play key roles in the provision of the NADPH required for lipid synthesis in M. alpina by homologous overexpression and RNA interference (RNAi) [9–13]. As there is a possibility that some NADPH might be formed via alternative pathways, the synthesis of NADPH for lipid biosynthesis in oleaginous micro-organisms is still not fully understood.…”